An injection device, where a gas bottle is charged with both high-pressure gas and contents such as a medicine, and the contents are injected from a gas injection valve fixedly provided in the opening portion of the gas bottle under gas pressure, is conventionally used. Hitherto, this type of the conventional injection device uses specified chloro-fluoro-carbon gas as a propellant. Due to an increased interest in environmental protection, there is the today's trend that the previously-noted specified chloro-fluoro-carbon gas is replaced by alternative chloro-fluoro-carbon gas such as HFC134a. Such alternative chloro-fluoro-carbon gas such as HFC134a exerts an influence on an ozone layer, but its influence on global warming is 1000 or more times greater than CO.sub.2. Pre-estimatedly, the increased tendency of using alternative chloro-fluoro-carbon gas maybe poses a new problem. For the reasons set forth above, more recently, there has been proposed and developed the use of various gases suitable for a propellant of an injection device, such as carbon dioxide gas, nitrogen gas, or inert gas (for example helium, neon, krypton, xenon, radon or the like), all gases having a less influence on depletion of ozonosphere and global warming. In case that either the above-mentioned gases is used as a propellant of the injection device, it is desirable to reduce the size of a gas bottle by way of liquefaction of gas to be charged in the same manner as chloro-fluoro-carbon gas liquefied for the propellant purpose. For example, in case of the use of liquefied carbon dioxide gas, its vapor pressure reaches 60 kgf/cm.sup.2 at 20.degree. C. In case of the use of inert gas, in order to increase a volumetric efficiency it is preferable to use a highly-pressurized, or liquefied inert gas. In the last analysis, it is desirable to use high-pressure gas having a pressure level of 50 kgf/cm.sup.2 or more. Such a conventional high-pressure gas injection valve has been disclosed in Japanese Patent Provisional Publication No. 8-141450.
FIG. 10 shows the conventional gas injection device disclosed in the previously-described Japanese Patent Provisional Publication, where a valve pin 3 is slidably received in a valve casing 2 fixedly connected to the opening portion 1a of a gas bottle 1, first and second seal rings 4 and 5 are in axially spaced relationship with each other and fitted to the interior of the valve casing 2, and a fixed-quantity chamber 6 is defined in a portion sandwiched by both the first and second seal rings 4 and 5 for capturing therein a fixed amount of gas before injection. Furthermore, a first valve portion 7 is provided at the lower end of the valve pin 3, so that the first valve portion is fitted to or brought into contact with the inside of the first seal ring 4 in a fluid-tight fashion when the valve pin 3 is pushed from the outside. Also provided at the upper end of the valve pin 3 is a second valve portion 8, which comprises a large-diameter portion 8a fitted to or brought into contact with the inside of the second seal ring 5 when the valve pin 3 is kept at its uppermost position, and a small-diameter portion 8b cooperating with the second seal ring 5 to define an aperture therebetween when the valve pin 3 is pushed from the outside. In addition to the above, a spring 9 is accommodated in the fixed-quantity chamber, so that the valve pin 3 is permanently biased upwards by means of the return spring 9. With the previously-noted arrangement of the gas injection valve, in a steady state where the valve pin 3 is not pushed from the outside, the large-diameter portion 8a of the second valve portion 8 is kept in contact with the inside wall of the second seal ring 5 in a fluid-tight fashion, whereas the first valve portion 7 remains spaced apart from the first seal ring 4. Thus, the interior of the gas bottle 1 communicates with the fixed-quantity chamber 6. When the valve pin 3 is pushed from the outside from such a steady state, the first valve portion 7 is brought into contact with the first seal ring 4 and thereafter the small-diameter portion 8b of the second valve portion 8 defines an aperture in cooperation with the second seal ring 5. This permits the contents to be injected together with the gas through the aperture into the exterior of the gas bottle 1. At this time, the first valve portion 7 is fitted to or brought into contact with the first seal ring 4 before the second valve portion 8 and the second seal ring 5 cooperate with each other to define the aperture therebetween, thereby blocking the fluid communication between the fixed-quantity chamber 6 and the interior of the gas bottle 1. This enables the fixed quantity of gas and contents captured in the fixed-quantity chamber 6 to be injected from the gas injection device.
In case that high-pressure gas such as liquefied carbon dioxide gas is used as a propellant of a gas injection device, a more strong structure of a gas bottle and a more strong structure of a gas injection valve are required from the viewpoint of safety. The more strong structure requires so much materials in manufacturing a gas bottle or a gas injection valve, as compared to the current injection device in which specified chloro-fluoro-carbon gas or the like is used as a propellant. For the reasons discussed above, same as at present, it is not preferable to use the injection device only once and then throw it, in view of efficient use of earth resources. However, the previously-described conventional gas injection valve does not have a structure that high-pressure gas and contents such as medicines are recharged into the internal space of the once-used gas bottle 1. Thus, it is impossible to recycle the prior-art gas injection valve and gas bottle 1 having the same structure as at present.
It is, therefore, in view of the previously-described disadvantages of the prior art, an object of the present invention to provide improved technologies for a gas injection valve and an injector adapter used as a gaseous fluid recharging adapter, while being fitted to the gas injection valve, which is capable of easily recharging high-pressure gas into the once-used gas bottle in spite of its simple structure, and of making efficient use of earth resources without introducing an increase in production cost.